Rolling element intermediate shaft assembly

ABSTRACT

In one aspect, a rolling element intermediate shaft assembly is provided. The assembly includes a solid shaft having a first end and a second end and a tubular shaft configured to receive the shaft first end. The tubular shaft includes an inner wall with an axially extending groove formed therein, and the axially extending groove includes an inner surface. The assembly further includes a wear plate having a bottom surface and defining an axially extending channel, the wear plate being received in the tubular shaft axially extending groove, and at least one ball bearing disposed within the wear plate channel between the wear plate and the solid shaft.

CROSS-REFERENCES TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional Patent Application Ser. No. 61/825,884 filed May 21, 2013, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present disclosure generally relates to shaft couplings and, more specifically, to intermediate shaft assemblies for vehicles.

BACKGROUND OF THE INVENTION

Intermediate shafts (I-shafts) are designed to be a component of torque transfer from a steering column to a steering gear. They may also allow axial movement while maintaining this ability to transfer torque. Some known I-shafts control the torsional rate and axial sliding force through clearance control and friction, and these I-shafts are commonly referred to as friction slider I-shafts.

Some know friction slider I-shafts are composed of a metal solid shaft with a plastic based coating sliding inside of a metal tube. Many of these friction sliders must maintain extremely tight tolerances. As a result, because cross-sections of these components vary by application, the plastic based coating that is placed over the metal solid shaft must be customized to fit the specific tube it will be positioned in. As such, this process is difficult to use and maintain on a mass production scale. Accordingly, it is desirable to provide an I-shaft with variable tolerances such that it may be used with various sized I-shaft components.

SUMMARY OF THE INVENTION

In one aspect, an elastic wear plate for a rolling element intermediate shaft assembly having a tubular shaft with an axially extending groove formed in an inner surface of the tubular shaft is provided. The wear plate includes a body having a first end and a second end. The body defines an axially extending channel configured to receive a plurality of ball bearings, and the body is configured to be oriented within the axially extending groove of the tubular shaft.

In another aspect, a rolling element intermediate shaft assembly is provided. The assembly includes a solid shaft having a first end and a second end and a tubular shaft configured to receive the shaft first end. The tubular shaft includes an inner wall with an axially extending groove formed therein, and the axially extending groove includes an inner surface. The assembly further includes a wear plate having a bottom surface and defining an axially extending channel, the wear plate being received in the tubular shaft axially extending groove, and at least one ball bearing disposed within the wear plate channel between the wear plate and the solid shaft.

In yet another aspect, a method of assembling a rolling element intermediate shaft assembly is provided. The method includes providing a solid shaft having a first end and a second end, providing a tubular shaft having an inner wall with an axially extending groove formed therein, the axially extending groove having an inner surface, and providing a wear plate having a bottom surface and defining an axially extending channel. The method further includes orienting the wear plate in the tubular shaft axially extending groove, inserting the solid shaft into the tubular shaft, and inserting at least one ball bearing within the wear plate channel between the wear plate and the solid shaft.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is an exploded view of a rolling element I-shaft assembly in accordance with the invention;

FIG. 2 is a perspective view of an exemplary solid shaft of the I-shaft assembly shown in FIG. 1;

FIG. 3 is a perspective view of an exemplary wear plate of the I-shaft assembly shown in FIG. 1;

FIG. 4 is a perspective view of an exemplary tubular shaft of the I-shaft assembly shown in FIG. 1;

FIG. 5 is a cross-sectional view of a portion of the I-shaft assembly shown in FIG. 1, after assembly, and taken along line 5-5;

FIG. 6 is a sectional view of the I-shaft assembly shown in FIG. 5, and taken along line 6-6; and

FIG. 7 is an enlarged view of a portion of the I-shaft assembly shown in FIG. 6, and taken along section 7.

DETAILED DESCRIPTION

Referring now to the Figures, where the invention will be described with reference to specific embodiments, without limiting same, FIG. 1 illustrates an exemplary rolling element intermediate shaft (I-shaft) assembly 10 that generally includes a yoke 12, a solid shaft 14, a roller assembly 16, and a tubular shaft 18. Roller assembly 16 includes a cap 20, ball bearings 22, and wear plates 24. In the exemplary embodiment, I-shaft assembly 10 is configured for use in a vehicle steering column assembly (not shown). However, shaft assembly 10 described herein may be used in any other suitable system.

FIG. 2 illustrates solid shaft 14, which generally includes a solid body 26 having a first end 28 and a second end 30. First end 28 is configured for insertion into an aperture 32 of yoke 12 (see FIG. 1) to facilitate coupling therebetween, and second end 30 is configured for insertion into tubular shaft 18. Solid body 26 includes grooves 34 extending axially along the length of solid shaft 14.

FIG. 3 illustrates wear plate 24, which generally includes a body 36 having a first end 38 and a second end 40. First end 38 includes arms 42 configured to facilitate holding wear plate 24 in position within tubular shaft 18 (e.g., arms 42 hook on tubular shaft 18), and second end 40 includes a tab 44 configured to facilitate preventing ball bearings 22 from rolling out of grooves 34 if solid shaft 14 is extended past wear plates 24. Wear plate body 36 defines an axially extending track or channel 46 that is configured to receive ball bearings 22, as is described herein in more detail. Wear plate first end 38 is configured to be inserted into cap 20, and wear plate second end 40 is configured to be inserted into tubular shaft 18. Wear plate 24 is of a material capable of elastically deforming within tubular shaft grooves 54 in response to a transverse force directed from ball bearings 22.

FIG. 4 illustrates tubular shaft 18, which generally includes a tubular body 48 having an open end 50 and a yoke end 52. Open end 50 is configured to receive roller assembly 16 and solid shaft second end 30, and yoke end 52 is configured to couple to the steering column assembly. Tubular body 48 includes an inner wall 53 having axially extending grooves 54 formed therein. Grooves 54 are configured to receive wear plates 24 at least partially therein, as is describe herein in more detail. Tubular body 48 also includes one or more slot 56 configured to retain cap 20 on tubular shaft open end 50. However, cap 20 may be coupled to tubular shaft 18 in any suitable manner.

With reference to FIGS. 5-7, assembly of I-shaft assembly 10 includes providing yoke 12, solid shaft 14, roller assembly 16, and tubular shaft 18. Wear plates 24 are inserted into tubular shaft open end 50 and are each oriented within one of tubular shaft grooves 54 such that bottom surfaces 58 of wear plates 24 are facing inner surfaces 60 of grooves 54 (see FIGS. 6 and 7). As shown in FIG. 7, wear plate 24 and/or groove 54 are formed such that bottom surface 58 is oriented with respect to inner surface 60 at an angle ‘α’ that is transverse to the axially extending grooves 54. In the exemplary embodiment, angle ‘α’ is less than or equal to 10°. However, angle ‘α’ may be any suitable angle that enables I-shaft assembly 10 to function as described herein. The offset between the surfaces 58, 60 due to angle ‘α’ facilitates a flexible or elastic interface between wear plate 24 and tubular shaft 18, which prevents or eliminates the need for exact matched pairs and tight tolerances between components 14, 16, 18 of I-shaft assembly 10. As such, the offset facilitates translational movement while minimizing fatigue of the wear plate and preventing movement of wear plates 24 when a torque is applies to assembly 10. Additionally, as described herein, the type of material used to fabricate wear plate 24, as well as the thickness of the material, may be varied to provide a desired elasticity or flexibility for wear plate 24.

Solid shaft second end 30 is inserted into tubular shaft open end 50 and oriented such that grooves 34 are substantially aligned with wear plates channels 46. As illustrated in FIG. 6, grooves 34, wear plates 24, and grooves 54 are oriented approximately 180° from each other. However, grooves 34, wear plates 24, and grooves 54 may be oriented with respect to each other at any suitable angle that enables assembly 10 to function as described herein. Further, assembly 10 may include any number of sets of grooves 34, wear plates 24, and grooves 54. For example, assembly 10 may include three or four sets of grooves 34, wear plates 24, and grooves 54.

In the exemplary assembly, ball bearings 22 are subsequently inserted into the spaces or tracks formed between grooves 34 and channels 46. During insertion of ball bearings 22, wear plates 24 may flex to take up any tolerance of assembly 10 due to the offset orientation of wear plate bottom surfaces 58 and tubular shaft groove inner surfaces 60, as described above. Cap 20 is inserted over solid shaft 14 and is coupled to tubular shaft open end 50 (see FIG. 5), which facilitates securing ball bearings 22 within wear plate channels 46 and preventing foreign objects or contaminants from getting into tubular shaft 18 and hindering the operation of roller assembly 16. Yoke 12 may then be coupled to solid shaft first end 28 in any suitable manner (e.g., press-fitting, welding, etc.).

Described herein are systems and methods for a rolling element I-shaft assembly that includes a tubular shaft, a solid shaft, wear plates, and ball bearings. Grooves are formed in the solid shaft outer surface and the tubular shaft inner surface. The wear plates include channels and are oriented within the tubular shaft grooves proximate the solid shaft grooves to define tracks therebetween to receive the ball bearings. This allows translational motion between the shafts as the ball bearings travel axially down the tracks. The wear plates also allow for variations along the solid shaft and tubular shaft by providing a flexible interface between the described components due to an offset angle between the wear plates and the tubular shaft. Accordingly, a robust I-shaft assembly is provided that facilitates translational motion, does not require high tolerances, and maintains high torsional strength, durability, and stiffness.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description. 

Having thus described the invention, it is claimed:
 1. A wear plate for a rolling element intermediate shaft assembly having a tubular shaft with an axially extending groove formed in an inner surface of the tubular shaft, the wear plate comprising: an elastically deformable body having a first end and a second end, the body defining an axially extending channel configured to receive a plurality of ball bearings, the body configured to be oriented within the axially extending groove of the tubular shaft.
 2. The wear plate of claim 1, further comprising a pair of arms extending from the body first end, the arms configured to hook onto the tubular shaft.
 3. The wear plate of claim 2, further comprising a tab extending from the body second end, the tab configured to retain the plurality of ball bearings in the axially extending channel.
 4. The wear plate of claim 1, wherein the body comprises a pair of bottom surfaces oriented to define an offset angle between the bottom surfaces and the tubular shaft axially extending groove.
 5. The wear plate of claim 5, wherein bottom surfaces are oriented to define an offset angle that is transverse to the axially extending groove of about between 0° and 10°.
 6. A rolling element intermediate shaft assembly comprising: a solid shaft having a first end and a second end; a tubular shaft configured to receive the shaft first end, the tubular shaft having an inner wall with an axially extending groove formed therein, the axially extending groove having an inner surface; a wear plate having a bottom surface and defining an axially extending channel, the wear plate received in the tubular shaft axially extending groove; and at least one ball bearing disposed within the wear plate channel between the wear plate and the solid shaft.
 7. The assembly of claim 6, further comprising: a second axially extending groove formed in the tubular shaft inner wall; and a second wear plate received in the tubular shaft second axially extending groove, wherein at least one ball bearing is disposed within the second wear plate channel between the second wear plate and the solid shaft.
 8. The assembly of claim 7, wherein the axially extending groove and the second axially extending groove are oriented approximately 180° apart from each other.
 9. The assembly of claim 8, wherein the wear plate and the second wear plate are oriented approximately 180° apart from each other.
 10. The assembly of claim 6, wherein an offset angle is defined between the wear plate bottom surface and the tubular shaft groove inner surface.
 11. The assembly of claim 10, wherein the offset angle that is transverse to the axially extending groove of about between 0° and 10°.
 12. The assembly of claim 6, wherein the solid shaft includes an outer surface having an axially extending groove formed therein, wherein the at least one ball bearing is disposed within the wear plate channel and the solid shaft axially extending groove.
 13. The assembly of 12, wherein the solid shaft includes a second axially extending groove formed therein.
 14. The assembly of claim 13, wherein the solid shaft axially extending groove and the solid shaft second axially extending groove are oriented approximately 180° apart from each other.
 15. The assembly of claim 6, further comprising a retainer cap coupled to the tubular shaft to facilitate retention of the at least one ball bearing within the tubular shaft.
 16. The assembly of claim 6, further comprising a yoke coupled to the solid shaft second end, wherein the tubular shaft further includes a yoke end.
 17. A method of assembling a rolling element intermediate shaft assembly, the method comprising: providing a solid shaft having a first end and a second end; providing a tubular shaft having an inner wall with an axially extending groove formed therein, the axially extending groove having an inner surface; providing a wear plate having a bottom surface and defining an axially extending channel; orienting the wear plate in the tubular shaft axially extending groove; inserting the solid shaft into the tubular shaft; inserting at least one ball bearing within the wear plate channel between the wear plate and the solid shaft.
 18. The method of claim 17, further comprising providing the wear plate with an angled bottom surface such that the angled bottom surface defines an offset angle between the wear plate bottom surface and the tubular shaft groove inner surface, wherein the offset angle is transverse to the axially extending groove by about between 0° and 10°.
 19. The method of claim 17, further comprising: providing the tubular shaft with a second axially extending groove; providing a second wear plate; orienting the second wear plate in the second axially extending groove; and inserting at least one ball bearing within the second wear plate channel between the second wear plate and the solid shaft.
 20. The method of claim 17, wherein the step of providing the solid shaft comprises providing a solid shaft having a first end, a second end, and an outer surface having an axially extending groove formed therein, and wherein the step of inserting at least one ball bearing comprises inserting at least one ball bearing within the wear plate channel and the solid shaft axially extending groove. 